New low-cost "hardware store" racing class; input on proposed rules

Are round masts really that much better than square ones?

 

Round vs. Square

Yes, better. Mostly because the stiffness of a square mast is different for bending in different directions... greater across the diagonal and less across the faces. It is twice as stiff in the diagonal directions. So the circular cross section ends up having the best stiffness to weight ratio when it is desirable to have uniform stiffness in bending in all directions. If you want a non-uniform stiffness, it is good to have a smooth transition as the bending direction changes. In that case an elliptical shape is best with the long axis of the ellipse in the direction where the most stiffness is desired. In general, the masts you can buy are approximately elliptical. Round is almost as good and easier to fabricate.

 

The main class I sail has had several aluminium masts available, the current ones are oval. But most in the class agree the best mast was the early one, a rounded diamond shape with the longest dimension being fore and aft.. sadly this extrusion is no longer available.
Anyone with the early mast looks after it. But as we sail in close quarter 6 inches apart in tree lined rivers, masts are often casualties.

My home built wooden masts have always been circular, but I have seen wooden masts both hollow and solid being oval ( longest dimension always fore and aft).

Unless you are going to either spend hours analysing the forces or get some one else to do it, then the way to go will always be circular.

 

Another Flavor

Here is my current (third) mast I built for the BLUE HERON. The trapezoidal piece in the middle of the cross section is one of a number of ribs. So, the mast is mostly hollow. It is 19 feet long and weighs just over 15 lb, #3 pine. The wooden sail track is structural and contributes to fore and aft stiffness and strength.

With the sail billowing out to leeward, it looks like (and hopefully acts like) an airplane wing with Kruger-flaps extended, increasing the lift produced by the main sail.

 

That's impressive, 15 lb! I think that's lighter than my aluminum Snipe mast.

 

hi folks,

It has been a while, heavy work schedule and a lot of other life distractions has keep me away from the site and boats in general. Sorry for my long absence, it appears many of you had questions for me. Though it looks like you all have been doing fine without me, though I have only skimmed through the last six months of postings, lots of reading them. lots of it interesting and informative.

Looks like the subject is alive and well, good to see the thread so active! All of you have been great, the contributions have been numerous and generally very good. keep up the good work.

I see the issue of used gear and rigging coming up, I like to salvage stuff to build cheap boats, but it does represent a dilemma. I do not want this to be come a see who can salvage better than the next guy. It would be an unfair advantage if someone lucks out to find a wreck or 2nd hand gear someone is getting rid of cheap. So use it, but figure in what a reasonable retail cost would be to buy it or make it yourself, if it could be home made. this should keep costly hardware out of the fleet, many times simple wood or plastic cleats work perfectly well, you just have to stay away from the boat yard the boat catalogs. Or you get stumped on how to solve the problem.

In the rules I think that the typical purchase price of the materials would be counted, so buying sails new or used, only the material costs would count. You can have sails made to save time, or buy a sewing machine and have at it yourself. BTW, used sewing machines are not that costly, about the same as a table saw. If you are using a lightweight home type sewing machine, it just means you have to be creative on how you sew through thick stack-ups or reinforcement. A typical approach might be so sew as many seams with your home machine you can, and than with it temp taped or stitched, take it to an local upholstery place to have them sew the heavy duty seams.

And of course there is always using carpet tape or similar and avoid sewing at all.

the idea is to be creative in how you use low cost materials.

It will be interesting to see if cheap wing sails can be made to work well, or some hybrid or modified shape. sail area is not limited, but that is not the only factor in how fast a boat goes around a course. In some of the contest boats I have built, we have made smaller and better designed sails than some of the others who just strung up very large shapeless tarps, we always out-sailed, even down wind, the larger sails. One of the reasons I crafted the rules the way they are, to see if some creativity can develop faster rigs.

 

Naiad - First Sail

Today was the day for the first sail. I got Naiad all trailered up and ready for the 4 mile trip to Lake Washington. Riles, my stalwart crew, helped with the rigging. Segler did too; then he took his 'big boat' (35 ft. yawl) out with my wife aboard so she could continue taking pictures. We sailed out of the marina, sailed about for an hour or so, and sailed back in. The wind was 7 - 11 knots and variable; a beautiful day. Everything worked, nothing broke, and there were no spontaneous capsize recovery practices. I was pleased with the balance and the roll stability. Helm was very neutral; but I can move the dagger-board about six inches fore and aft so the helm pressure can be easily optimized. The boat, as it stands, is into my budget by $350 USD, but is currently using blocks from my stash left over from 5o5 sailing, and free used sails from a 420. So I have blocks and sails to make before all is 'legal'. Pictures courtesy of Donna.

 

Pictures of Naiad first sail...

Pictures failed to upload. I suspect Operator Error. Trying again...

 

She looks great. The cheapest new 420 sails I can find are on the site Richard Woods referenced:

http://www.intensitysails.com/420sails.html

 

That's a pretty major change in the rules, if you only count the cost of sail material and not the cost of building the sail. I suppose that if you have a lot of carbon fiber battens, that cost would be counted as well.

One thing that isn't clear to me is, does shipping cost count? If Dunnage buys 420 sails from Intensity, depending on whether everyone is comfortable with the rule change, he either pays what the material costs or what the sails cost, but it doesn't seem like he should have to include the cost of shipping the sails.

 

Sails for Naiad

I actually plan to make, not buy, my sails for Naiad. I already have a set of 420 sails that were given to me at no cost. I used them for the 'first sail' and will use them again until the home-made sails are finished. The 420 sails will also be the pattern for my home-made sails. I found, on e-Bay, a source for 4 oz. Dacron sailcloth for $6.99 USD per yard (and the bolt is 65 inches wide). So that is $3.88 per square yard or $3.25 per square meter. Really inexpensive! I also have seam tape and thread and brass grommets that I have bought. So my set of sails is eventually going to cost less than $100 (for both sails, not each). After that, I will need to build about a dozen blocks. The Harken and Ronstan blocks I am using now were odd bits that I had left over from when I owned and sailed a 5o5. I will also change the hardware store 'awning cleats' currently used for some wooden cleats that are like horn cleats, but with one horn undercut at a ten degree V to wedge the rope. Faster, better, cheaper... So I am pretty confident that the cost target is easily met.

 

On using Intensity 420 Sails

The short answer is that they are too expensive. The set of sails, main plus jib is $320 USD, and that only if one uses the cheaper 'Power Head" mainsail. I have only about $275 left unspent in my budget. That has to provide for the sails and blocks that I am currently using 'out of rule'. But they are very nice and, by any other measure, very inexpensive.

 

Carbon Fiber Battens

You all may want to know of a resource I found for battens. There is a small manufacturing business in Mt. Vernon, Washington State, USA - Goodwinds LLC (goodwinds.com)- that makes carbon rods and tubes. They started out making structural parts for kite builders and model airplane builders.

They have a flat rod that is 'just right' for us: Part No. 020136 (.437" x .070" x 48" Solid Flat Carbon) 1.280 oz. $10.59 USD in quantity less than six.

So you might consider kite / model airplane suppliers in general as a source for battens. I think that one batten in the 420 pattern sail I am making is all that is needed... at least the 420 mainsail I have sets well with only the (long) top batten fitted.

 

how is that a change in the rules? all along it was material costs only, and the method of construction should be suitable for a typical home shop. so injection molded carbon graphite fittings would not qualify, but hand laid up parts would be.

do not count shipping costs, this was discussed. it would put people in remote areas at a disadvantage since they would have to purchase all supplies mail order. it is just nominal retail price of the materials only. As long as you can find a source of materials that is available for anyone to buy in small qualities, that is good enough. Realize it is an honor thing (at least to start).

 

Congrats Dunnage,

looks like a nice little boat at any price, it is even more attractive knowing it did not cost much to build and put on the water.

that is the whole point of the rules: decent boats do not have to cost much.

Sail cloth is certainly an excellent choice, but do not dismiss other materials that may make decent sail cloth that may cost less.